Seems very similar, fabric face weight on the FL seems thicker but is woven in the same way as the Ambient/MDWi. Overall I really like it but wish it was a full zip. It’s a touch heavy at 12.6 oz for a large. As for boxy, it fits me and I don’t see a big difference in fit between the 3 below.
Left is Ambient, middle First Lite Navigator, right is MDWi.
Hard to see the similar weave pattern (grid structure), but here is MDWi - First Lite. Overall it feels like the FL piece would be more durable.
Lastly, to confirm it is an exposed insulation type and not a lofted Sherpa type, you can see the attachment method here. Looks exactly like the Sitka/MDWi.
I will get a couple more when Fusion and Cerca are released just because I like those patterns and these types of garments. But again, it’ll take a full zip version to make me eliminate use of the Sitka versions. I also can’t comment on warmth because it’s 90* here already, however I tend to like the lower gram insulation of the MDWi so I fear the FL piece may be too warm for most uses for me.